Sanitary napkin



Oct. 1, 1968 HOEY ET AL 3,403,681

SANITARY NAPKIN Filed Sept. 23, 1965 United States Patent 3,403,681SANITARY NAPKIN Raymond M. Hoey and Donald Patience, Barrington, Ill.,assignors to The Kendall Company, Boston, Mass., a corporation ofMassachusetts Filed Sept. 23, 1965, Ser. No. 489,612 6 Claims. (Cl.128-290) ABSTRACT OF THE DISCLOSURE The fluff absorptive core of asanitary napkin is provided with lined channels leading from the topsurface thereof into and terminating in the body of the core. A fluidconducting sheet covering the top surface follows at least a major partof the way into the channels and serves as a channel liner. The corecontains regions of different fluff densities.

This invention relates to sanitary napkinsv More particularly, thisinvention is directed to sanitary napkins wherein a mass of looselyassociated fibers serve as the major fluid absorption or collectioncomponent of the napkin.

Sanitary napkins of the type to which this invention is directed aresometimes referred to as absorbent fluff type napkins, taking the nameof the commonly used fibrous mass of comminuted wood pulp used as theabsorption or collection component of the napkin, although fibers otherthan wood pulp fibers, such as shredded cellulose fibers generally, maybe used. Popular acceptance of fluff napkins in no small measure is dueto the inexpensiveness of fibrous pads or batts of this nature, eventhough the fluff itself lacks certain desirable absorption properties.Fluff itself, for example, has relatively poor fluid conductive powers:fluid placed upon the surface of a fluff pad is readily absorbed by thepad, but does not rapidly spread laterally from the site of the appliedfluid. Various proposals have been made to overcome this deficiency,some of which have been adopted commercially when consistent with theeconomies of employing fluff in the manufacture of these sanitarynapkins.

The type of napkin to which this invention is directed is the type inwhich the fluff mass (either wood pulp fibers or others) forms the coreof the napkin and is covered on at least one surface thereof with one ormore absorbent, fluid pervious sheets having capillary properties todistribute or conduct the fluid laterally over the core surface. Thistype napkin is well known and normally includes a fluid barriercomponent and an overwrap sheet confining all of the napkin componentsin a unitary assembly.

The fluid distributing sheet may be any soft, conformable, pervious,absorbent sheet material having the stated desired capillarity.Consistent with the economies of this product, creped tissue or waddingare commonly used. The creped tissue is positioned on the surface of thefluff core which is placed toward the body when in use and covers atleast the central portion of this surface. In some instances this tissuesheet may be Wrapped around the pad, in which case the tissue may serveas the wrapper to confine the loosely associated fibers of the fluff.For reasons known in the art, it is preferred to overwrap the fluff coreand tissue with a fluid permeable, textile fabric. This textile fabricoverwrap or outerwrap is the napkin component which is in contact withthe body When in use. It is highly pervious to fluids, is less fluidconductive than the fluid conductive cover sheet and may even besomewhat water repellant. The textile fabric may either be a nonwoven orwoven fabric. Examples of textile fabric overwraps are gauze, scrim, andnonwoven fabrics. The

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fluid barrier component may be any suitable water repellant orimpermeable sheeting. It may be positioned next to and cover theunderside surface of the fluff core. As its name indicates, its functionis to prevent fluid from striking through the napkin. Plastic films andwater repellant fibrous sheets are examples of these barrier sheets.

It is an object of this invention to provide a fluff sanitary napkinimproved with respect to the rate of the napkin to absorb menstrual orlochial fluids.

Another object of this invention is to provide a fluff sanitary napkinhaving improved distribution of fluids in the fluff.

Another object of this invention is to provide a fluff sanitary napkinimproved with respect to utilization of the absorption capacities of thefluff.

A further object of this invention is to provide a fluff sanitary napkinimproved with respect to retention of fluids absorbed in the fluff.

A still further object of this invention is a fluff sanitary napkinimproved with respect to rate and capacity of the napkin to absorb,collect, retain and distribute fluid exudates in the napkin.

A still further object of this invention is to provide a fluff sanitarynapkin within the objectives set forth above in a manner consistent withmanufacturing economies of prior fluff napkins.

In accordance with this invention, the fluff core of a sanitary napkinis provided with a plurality of channels leading from a surface thereofinto and terminating in the body of the core. The channels terminateshort of the opposite surface of the core so that the channels are eachsurrounded by a concentration of fibers decreasing in density in alldirections within the core from the walls of the channels, including theterminal bottom portions there-of. The fluid conducting or distributingsheet follows at least a major part of the way into the channels. Theportions of the sheet inside the channels are held in place on the wallsthereof and against displacement therefrom by engagement with the fibersin the core.

Specific constructions of the napkins of this invention, from which theabove mentioned and other objects of the invention will be apparent tothose skilled in the art, are set forth in the following description andin the drawings in which:

FIQ. 1 is a plan view of a sanitary napkin of this inventlon;

FIG. 2 is an enlarged cross-sectional view of the flufl" core portion ofthe napkin of FIG. 1; and

FIG. 3 is a generally schematic view of an apparatus for manufacturingthe napkins in accordance with this invention in which the napkincomponents shown are in cross section.

The sanitary napkin 10 in FIG. 1 is shown with a nonwoven fabricouterwrap .11 which in its wrapped on form is of greater length than thecore of napkin. The portions 12 of the outerwrap extending beyond thecore ends may serve as tabs for attachment to a belt or the like to holdthe napkin in place upon the body. The textile fabric outerwrap inaddition to having the aforedescribed properties must be of suflicientstrength for this purpose.

In the embodiment of the invention of FIGS. 1 and 2 the nonwoven fabricouterwrap 11 is shown with a plurality of apertures 13 overlying thefluff core 14 and in register with the openings of the channels 15 atthe surface of the core. The apertures 13 conveniently may be formed inthe overwrap 11 at the same time that the channels 15 are formed in thecore and lined with the fluid conductive cover sheet 16. As will besubsequently explained, the apertures may be formed in such manner thatthe fibers of the outerwrap are parted and grouped to form theperipheral edges of the apertures. These groupings of fibers provideareas of greater capillary attraction for fluids than the non-aperturedareas of the nonwoven fabric between the apertures. This tends topromote the flow of fluid deposited on these areas to the apertures forentrance to the channels in register therewith. The registration betweenthe apertures and the channels also permits unimpeded entry of fluids tothe channels for fluid deposited thereover.

The fluid conductive sheet 16, such as creped tissue conventionallyemployed in fluff-type napkins, is positioned on a flat surface of thefluff core as shown in FIG. 2 and follows into and lines the channels15. The creped tissue sheet 16 is pressed into the core in forming thechannels 15 and into intimate contact with the core fibers at theinterface between the sheet and the fibers in channel walls. Theintimate contact with the fibers serves to aid in holding the sheetagainst dislodgement from the channels.

The creped tissue sheet should extend at least a major part of the way,say, at least about one-half of the channel depth, in to the channel.When depressed only partway into a channel, the tissue sheet, of course,lines only a portion of the side walls of channel to the extent that thesheet is depressed to follow into the channel. The terminal bottomportion of the sheet may remain continuous, thus spanning the terminalbottom portion of channel. Alternatively, and preferably, the terminalbottom portion of the sheet in the channel may be ruptured to form anaperture therein. The fibers of the creped sheet at the periphery ofsuch an aperture intertangle with core fibers of the channel wall toprovide a positive interlocking engagement with the core, particularlywhen the aperture is located near or at the terminal bottom portion of atapering channel.

The aperture which may be formed by rupture of the sheet 16 at theterminal bottom portion of a channel, as at 17 in FIG. 2 provides aready exit for fluids in the channel to the core fibers. The crepedtissue is deformable and sufficiently pliant to follow at least part-wayinto the channel depressions rather than to part at the point ofpressure and form an aperture as in the case of the nonwoven fabricouterwrap 11. It is one of the advantages of this invention that thepractice thereof does not require the development of new components or asubstitution of components for the components presently in use in manysanitary napkins now commercially available.

The numeral 18 designates regions of dense concentra tions of fibers inthe fluff core 14 immediately surround ing the channels. Theconcentration of fibers in these regions is greater than theconcentration of fibers in the other regions in the core adjacentthereto and spaced from the channels. The dense regions 18 exhibitgreater absorption and distribution properties than other regions in thefluff core. In combination with the fluid distribution sheet 16 in thestructure of this invention the fluid is rapidly directed into theinterior of the fluff core. The function of the fluid distribution sheet16, as to its fluid distribution properties, is essentially the same asin the case of the same sheet covering the substantially flat, planersurface of the core in a conventional sanitary napkin. In the presentinvention, however, the sheet 16 lining the walls or portions of thewalls of the channels 15 positively direct and distribute the fluid intothe body of the fluff core 14 and thus rapidly remove the fluid from thebody surface of the wearer of the napkin. The fluid is brought intocontact with the high concentrations of fluff fibers in the interior ofthe core surrounding the channels for rapid distribution to regions ofthe core further into the interior of the core and hence further removedfrom the body of the wearer. It will be appreciated that thedensification of fibers not only around the side walls but also theterminal bottom portions of the channels provides for the collection andconcentration of fluids in regions 4 removed from the napkins topsurface, as viewed in FIG. 1. Strike through of fluid at the bottom ofthe pad is prevented by means of barrier sheet 19.

The channels 15 may extend to any depth in the fluff core 14. There is apreference for the present napkins wherein the channels terminate at adepth not more than midway between the top and bottom surfaces of thepad. The cross-sectional shape of the channel opening is a matter ofchoice, but substantially circular shapes are preferred. The channelneed not be a right angle cylinder in shape and preferably may havetapering side walls, tapering to a point at the terminal bottom portionof the channel.

The channels are located in at least the central portion of the napkinwhich normally is the site of initial contact with the fluid exudate.Channels may be located as well in the remaining portions of the napkindefined by the edges of the core as shown in the drawings. Sanitarynapkins having as few as about ten uniformly spaced channels per squareinch of the napkin surface area and channel openings of about indiameter have been found to function satisfactorily in accordance withthe invention. The size of the openings at the surface of the napkin andthe number of the channels may be chosen to satisfy the conditions ofuse to which the napkin is to be put. Generally, the size of the channelopenings and the number of channels should not be so great as to resultin a highly dimpled surface effect which may cause a feeling ofdiscomfort in normal use.

The channels may be formed in the pad and lined with the cover sheet inthe manner illustrated in FIG. 3. As shown in this figure, the fluff ispositioned as a core 14 between a sheet 16 of creped tissue and abarrier sheet 19. This composite is introduced into a nip between thetips of protuberances 22 on a roll 20 and the smooth surface of a roll21. Th rolls rotate counterclockwise with respect to each other as shownby the directional arrows on the rolls. The material moves through thenip from the right to left as viewed in the drawings. In passing betweenthe rolls, the protuberance 22 which may be coneshaped presses upon thecover sheet 16 pushing it into the core. The fluff fibers immediatelybeneath are pushed aside and down, resulting in a greater accumulation,and in some instances, compaction of fibers immediately around thchannel thus formed. As shown, the cover sheet 6 is also pressed intothe channel, at least partially lining the walls thereof. Due to thepressure or the configuration of the very tip of the protuberance, thesheet 16 may be ruptured at the bottom portion of the channel. Uponremoval of the protuberance 22 some fluff fibers may enter the rupturedopening in the sheet and become engaged with the peripheral edge of theopening. The fibers extending through the opening into the channelprovide added wicking action for removal of fluid in the channel.

The invention claimed is:

1. A sanitary napkin comprising:

(a) a core of loosely associated, fluid absorbent fibers having a topsurface and opposite thereto a substantially planar bottom surface, saidcore having a plurality of channels leading from the top surface thereofinto the body of said core and terminating therein short of the bottomsurface of said core, said loosely associated fibers occupying theregions with in the core between the channels and between the surfacesof said core so that the channels are each surrounded by fibers of thecore, the regions of the core immediately adjacent each of the channelshaving a denser concentration of fibers than regions spaced therefrombetween the channels and regions between the terminal bottom portions ofsaid channels and said bottom surface of the core;

(b) a soft, conformable, fluid pervious, absorbent sheet covering saidtop surface and following at least a major portion of the way into saidchannels in lining contact with the walls thereof, said sheet havingapertures therein located near the terminal bottom portion of saidchannels, said sheet engaged with said fibers surrounding said channelsand fibers of said sheet at the peripheral edges of said aperturesentangled with core fibers at the terminal bottom portions of saidchannels to maintain said sheet as a contiguous liner for said channels;and

(c) a fluid barrier sheet underlying the terminal bottom portions ofsaid chanels.

2. A sanitary napkin comprising:

(a) a core of loosely associated, fluid absorbent fibers having a topsurface and opposite thereto a substantially planar bottom surface, saidcore having a plurality of channels leading from the top surface thereofinto the body of said core and terminating therein short of the bottomsurface of said core, said loosely associated fibers occupying theregions within the core between the channels and between the surfaces ofsaid core so that the channels are each surrounded by fibers of thecore, the regions of the core immediately adjacent each of the channelshaving a denser concentration of fibers than regions spaced therefrombetween the channels and regions between the terminal bottom portion ofsaid channels and said bottom surface of the core;

(b) a soft, conformable, fluid pervious, absorbent tissue sheet coveringsaid top surface and following at least a major part of the way intosaid channels in lining contact with the walls thereof, said sheethaving apertures therein located near the terminal bottom portion ofsaid channels, said sheet engaged with fibers of said core at theinterface between said sheet and core in the walls of said channels andfibers of said sheet at the peripheral edges of said apertures entangledwith core fibers at the terminal bottom portions of said channels tomaintain said sheet as a contiguous liner for said channels; and

(c) a fluid barrier sheet underlying the terminal bottom portions ofsaid channels.

3. A sanitary napkin in accordance with claim 2 wherein said terminalbottom portions of said channels are located at a distance not more thanabout one-half the distance between the top surface and the bottomopposite surface of said core.

4. A sanitary napkin in accordance with claim 2 wherein said core andsaid tissue sheet are encased in a fluid pervious wrapper havingapertures therein in register with the openings of said channels.

5. A sanitary napkin in accordance with claim 2 wherein said barriersheet is positioned on said bottom surface, said tissue sheet extendsaround and at least partly over the bottom surface of said core andwherein said core and tissue sheet cover are encased in a fluid perviouswrapper having apertures therein in register with the openings of saidchannels.

6. A sanitary napkin in accordance with claim 2 wherein said barriersheet is positioned on said bottom surface, said tissue sheet extendsaround and at least partly over the bottom surface of said core andwherein said core and tissue sheet are encased in a fluid perviousWrapper having apertures therein in register with the openings of saidchannels.

References Cited UNITED STATES PATENTS 2,788,003 4/1957 Morin l28-2842,890,700 6/ 1959 Lonberg-Holm 128-284 3,046,986 7/1962 Harwood 1282903,060,936 10/ 1962 Burgeni 128290 3,315,676 4/1967 Cooper 128--287CHARLES F. ROSENBAUM, Primary Examiner.

